On C10 early forks normal oil level is approximately 14 inches at full extension per factory. This results in a 8 inch measure compressed approximately.

The following is a result of other comparisons:

On same fork 13" extended is to 6" compressed.12.5" extended is to 5.5" compressed for further comparison.

Not quite a linear progression. I noted that the emulator in my fork was just covered at the 14 and 8" measure point and so suspect oil levels past that became more linear as only oil was being measured. As I was rounding, more accurate measuring might have been more linear. But not by much.

The more oil in fork to a max of 5.12" would control last 1/3 of fork travel and limit brake dive according to Race Tech. My choice was to use 5.5" as my limit as I did not want to shorten fork travel by hydro locking fork in compression too early.

I am currently using 5.5 compressed/12.5 extended to control brake dive as fully as practical. Air assist is disabled by plug of balance holes. I am very happy with the current result.

This measure point might not be everyone as brake dive preferences are subjective as is suspension feel. But for my road conditions I like it very much.